Land Rover Defender Electrical Library 3rd Edition Nas Rover Manual

CIRCUIT OPERATION
DEFENDER 90 NAS15CONDENSER FAN GRANT
On receipt of the Condenser Fan Request signal, the GEMS ECM applies a ground
(C634-3) for the Condenser Fan Relay coil (C59-4). Provided that a battery feed is
available at the relay coil (C59-2) from the Main Relay within the Engine Management
Relay Module (C157-3), the Condenser Fan Relay will energize.
With the Condenser Fan Relay energized, a feed from Fuse 16 (C581-12) passes to the
relay (C59-1) on a brown and white wire, through the closed...

CIRCUIT OPERATION
16DEFENDER 90 NASHEATER BLOWER
DESCRIPTION
The heater is operated from three sliding controls attached to the instrument binnacle.
Two of the controls regulate the temperature and air flow distribution.  The third control
operates the two speed heater blower.  The heater blower operates with the ignition
switch in position II.  
OPERATION
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by a brown wire.  Current passes through fusible link...

CIRCUIT OPERATION
DEFENDER 90 NAS17HEATED REAR WINDOW  
DESCRIPTION  
The heated rear window (HRW) draws a high current from the electrical system and to
prevent battery discharge, the HRW will only operate when the engine is running. The
functionality of the HRW is controlled by the multi-function ECU.  The HRW is operated
by depressing the non latching heated rear window switch, mounted on the dash panel.
The instrument panel warning light will illuminate to indicate that the HRW is operating.
The ECU...

CIRCUIT OPERATION
18DEFENDER 90 NASIllumination  
The HRW switch has illumination which operates with the sidelights.  Power from fusible
link 1 of the engine compartment fuse box passes through fusible link 4 of the engine
compartment fuse box (C573-2) and feeds the lighting switch (C41-1) on a brown wire.
The lighting switch (C41-2) is connected to fuse 11 of the passenger compartment fuse
box (C581-1) by a red wire.  When the lighting switch is turned on, power is supplied
through fuse 11 (C581-2) to...

CIRCUIT OPERATION
DEFENDER 90 NAS19WIPERS AND WASHERS  
DESCRIPTION  
The front windscreen wipers are controlled from the column switch and operate when the
ignition switch is in position II.  The wipers have 2 speed settings, along with 2 flick
wipe speeds and a single wipe facility.  An intermittent wipe function and programmed
wash wipe facility is controlled by the multi-function ECU.  
Moving the wiper switch down from the off position initiates the intermittent wipe
function.  Moving the wiper...

CIRCUIT OPERATION
20DEFENDER 90 NASSlow and fast speeds  
Fuse 18 of the passenger compartment fuse box (C581-16) is connected to the wash/wipe
switch (C278-6) via a header joint (C289) by the green wire. Moving the switch to the
slow speed position allows power to flow across the switch (C278-1) to the wiper motor
(C30-3) on the blue/light green wire.  The wiper motor is grounded (C30-1) on the black
wire and the wipers operate at slow speed. Moving the wiper switch to the fast position
allows power to...

CIRCUIT OPERATION
DEFENDER 90 NAS21through the park circuit until their park position is reached.  Approximately 5 seconds
later, the ECU energizes the front wiper relay for 1 second. The process repeats until
power to the ECU from the wiper switch is broken by positioning the wiper switch to the
off position or slow speed wipe position.  
Programmed wash/wipe function  
Depressing the end of the wiper switch operates the programmed wash/wipe function.
The washer switch (C278-6) is supplied from fuse 18...

CIRCUIT OPERATION
22DEFENDER 90 NASRear wash  
The rear wash switch (C73-5) is supplied from fuse 17 of the passenger compartment fuse
box (C581-14) on the green wire.  Depressing the wash switch allows power to flow
through the switch (C73-2) to the rear washer pump (C21-2) and ECU (C62-16) on
black/light green wires. The washer pump (C21-1) is grounded on the black wire and
operates until the switch is released. When the ECU receives a 12 volt signal from the
washer switch, the ECU energizes the rear...

CIRCUIT OPERATION
DEFENDER 90 NASREV: 9/9723EXTERIOR LAMPS - Brake and Reverse Lamps  
DESCRIPTION  
The brake lights on the rear of the vehicle illuminate with the ignition switched on and the
brake pedal depressed.  
The reverse lights on the rear of the vehicle illuminate with the ignition switched on and
the gear selector lever in reverse position.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through...

CIRCUIT OPERATION
24DEFENDER 90 NASEXTERIOR LAMPS - Head, Side and Number Plate Lamps 
DESCRIPTION  
The lights are operated from the lighting switch located on the steering column. The
lighting switch has 2 positions. Position 1 switches on the tail lights and front sidelights,
position 2 additionally switches on the front headlights.  When the headlights are on, the
column switch can be used to switch between main beam and dipped beam.  
The headlights can be flashed with the lights on or off, by...